Managing System Time And Ntp; Ntp And Plotting - Coyote Point Systems E350GX Installation And Administration Manual

Table of Contents

Managing System Time and NTP

Through Equalizer's Administrative Interface, you can:

•

set the time zone

•

set the system date and time

•

set up to three Network Time Protocol (NTP) servers, and enable or disable synchronization with these

servers

NTP is a protocol designed to synchronize the clocks of computers over a network. NTP on Equalizer is compatible

with servers running versions 1, 2, 3, or 4 of the NTP protocol. An RFC for NTPv4 has not been written; NTPv3 is

described in RFC 1305.

On Equalizer, NTP is used primarily to time various operations, to ensure accurate timestamps on log entries (with

respect to server and client log timing), and to allow for examination of the timing of log entries on two Equalizers

in a failover configuration.

NTP on Equalizer works by polling an NTP server defined through the Administrative Interface. The time between

polls of the NTP server is controlled by the minpoll and maxpoll NTP parameters, which default to 64 seconds

(1 min 4 sec) and 1024 seconds (~17 mins), respectively. The behavior of NTP is to poll with a frequency starting at

minpoll and then decrease polling frequency over time to maxpoll, as the accuracy of the local clock approaches the

accuracy of the remote server clock. The time it takes for the polling delay to increase from minpoll to maxpoll will

vary based on a number of factors, including the accuracy of the clocks on the client and server, network latency,

and other timing factors.

NTP calculates when the local and remote system clocks are sufficiently in sync to begin increasing the polling

delay towards maxpoll. When the accuracy of the two clocks is significantly different, or there is significant latency,

for example, the two clocks may never be in sufficient agreement to increase the delay towards maxpoll. In this

case, Equalizer will continue to sync approximately every 64 seconds. This behavior indicates that a different NTP

server should be chosen.

We do NOT recommend changing the default minpoll and maxpoll delays in the NTP configuration file, in order to

ensure an accurate system clock. NTP packets are very small and should not cause any problems with Equalizer or

network operation, except as described in the following section.

NTP and Plotting

When you initially configure NTP, this may effectively disable plotting until NTP completes the initial

synchronization of Equalizer's system clock with the NTP server -- which may take from several hours to several

days. This is because plotting depends on accurate timestamps in the plot log. Since initially NTP is adjusting the

time at frequent intervals, the timestamps in the plot log may become out of sync with the system clock, and so no

plot data may be returned. Once NTP is no longer making adjustments to the system clock, plotting will function

normally.

Equalizer Installation and Administration Guide